It might bet the batttery but it sounds like you set the time zone and not the time instructions are here
This guide will take you through the process of changing the date, time and timezone in Windows XP.
Changing the date and time
The first thing to do is double click the clock on the taskbar, you will be presented with the Windows XP Date and Time Properties box.
In
fig 1.1 above you can see an example of a typical Windows XP Date and Time Properties box, we have pointed out the areas of interest.
To adjust the date use the monthly calendar (
A) along with the month selector (
B) and year selector (
C).
To adjust the time, click on the part of the time you want to change (hour or minutes)
D and then use the up and down arrows (
E) to change it.
To adjust the timezone click on the
Timezone tab (
F) and then select your timezone from the selection tool provided.
The
Internet Time tab (
G) allows you to synchronise your PC's clock with an internet server.